This invention relates to N-alkylpolyamines of the formula R--[NH(CH.sub.2).sub.x ].sub.y --NHR', and their use as curing agents for epoxy resins, where R is an aliphatic, hydrocarbon radical of from 5 through 8 carbon atoms, R' is H, R or R", x is an integer of 2 or 3 and y is an integer of 2 through 4. A monoepoxide adduct of the monoalkyl substituted polyamine is also disclosed wherein R" may then become an aliphatic substituent (2-14 carbon atoms) which may contain (a) an oxygen atom, (b) a hydroxyl group or (c) an aromatic substituent such as a phenyl ring.
It is known that epoxy resins having more than one oxirane group per molecule, can be cured with a wide variety of polyfunctional compounds to hard, insoluble and infusible products having many practical uses, including coatings and adhesives. One general text relating thereto is "Epoxy Resins, Their Application and Technology", by Henry Lee and Kris Neville, McGraw, Hill Book Company, Inc. copyright 1957.
Among the various curing agents are the aliphatic alkylene polyamines, such as diethylene triamine and triethylene tetramine. Because of certain limitations such polyamines have been used in modified forms, such as alkyl derivatives. Thus, on page 70 of the Lee and Neville text, there is disclosed a modified diethylene triamine in which one of the primary amine groups is substituted with a 12 carbon atom aliphatic chain. This compound is also described in a Monsanto data sheet dated Feb. 24, 1955 as a C.sub.12 aliphatic substituted diethylene triamine.
U.S. Pat. No. 3,291,775 discloses a process of curing polyepoxides with a polyimine or ketimines, such as those obtained by reacting a ketone with a polyamine. The products are exemplified therein by the formula ##STR1## where ##STR2## is the residue from a ketone. Such compounds, on exposure to moisture, decompose to form the original ketone and polyamine which, accordingly, cures in the same manner as the polyamine itself with the volatile ketone being evolved. The products are, accordingly, subject substantially to the same limitation as in the polyamine itself.
U.S. Pat. No. 3,280,074 discloses a curing agent such as a monotertiary-diprimary triamine which is similar to the Amine ODT noted above but having an aliphatic hydrocarbon radical of 12-22 carbon atoms substituted on the middle nitrogen of diethylene triamine so that the secondary nitrogen of the diethylene triamine is converted to a tertiary nitrogen.